Mpcci 学习.doc

MpCCI 学习首先启动MpCCI，配置完成后，在Go step中首先Start MpCCI，然后Start Fluent、Start Abaqus。在fluent的开始界面中，首先initial，然后设置迭代参数，time step size不但要与前面的abauqs的constant coupling time step相一致【应与abaqusEdit StepIncrementationInitial increment size相同】。还要与MpCCICoupling StepGlobalQuantityConfigurationDefault value(s)一致。【注意：此处设置了DeltaTime为Global则在Go Step中，不能选中 Constant coupling time step，并指定the coupling time step size】Fluent中Number of Time Steps=xxx；xxx*time step size与abaqusEdit StepBasicTime period相同。？When you create a coupled simulation project, the MpCCI GUI generates a set of files containing the definition of the coupled simulation model, e. g. the MpCCI input file and the MpCCI log files. Consequently, before you start the MpCCI GUI, you should move to a directory where you have permission to create files.You execute MpCCI GUI by running the mpcci executable with the gui subcommand and the desired options.Mpcci gui OPTIONS project OPTIONSOptions:-chwd Replace the symbolic working directory $(CWD)used inside the projectfile by the absolutepathname specified in the argument.-new Start the GUI with a new project.Before starting a coupled simulation you have to establish a project by using the action Save As from the File menu. 开始模拟前，使用File menu中的Save as创建project。Project file产生input file，同时包含在MpCCI GUI中设置。FileSave Project As saves the project settings under a speci_ed name. The MpCCI GUI displays the SaveAs dialog box. The active project can be renamed and saved to a new directory.To start an MpCCI job in batch mode with a well prepared coupled simulation project use:mpcci -batch If you start the MpCCI GUI without any options likempcci guithe following default checks are performed:_ Check and preparation of your environment._ A check of your secure shell rsa/dsa key files. If no rsa/dsa key files are found you will be asked to create them._ Check for an existing project file in the current directory in order to load that project to the MpCCI GUI. If more than one project file exists no project will be loaded._ Check of the license environment. MpCCI GUI tries to check for a license e. g. MPCCI LICENSE FILE and also informs you when your license will soon expire. In order to disable it use the option -nolic.If you do not include the to the mpcci gui the MpCCI GUI starts at the initial step.Coupling Stepusage of the same model dimension by the coupled codes.usage of appropriate solution types by the coupled codes. The solution types will be found by the scanner and may be static, transient or undefined. Different types in the model files lead to a warning message. Undefined types are treated as being proper.MpCCI 名字物理含义DeltaTime时间步长AbsPressure绝对压力OverPressure相对压力 prel = pabs prefWallForce壁面力 (absolute pressure + friction)RelWallForce相对壁面力 (relative pressure + friction)NPosition节点位置NDisplacement节点位移WallHTCoeff换热系数FilmTemp薄膜温度WallTemp壁面温度WallHeatFlux壁面热流LorentzForceLorentz 力密度向量JouleHeat体积 Joule热密度初始的交换“initial quantities transfer” 能设置成以下四种: “send”- 第一次交换中只发送数据 “receive”- 第一次交换只接受数据(程序等待数据) 【abaqus用】相当于此时接收到fluent的载荷【在求解前交换】 “exchange”- 发送数据,然后程序等待接受数据 【Fluent用】相当于此时fluent先计算然后输出pressure或friction的载荷到abaqus，然后等待abaqus返回Nposition【在求解后交换】 “skip” (or “none”)- 第一次交换没有动作耦合算法的结构第一步: 首先检查在求解前或求解后是否交换例子: 程序A在求解后交换 程序B在求解前交换 起始交换:- 程序A: exchange- 程序B: receive时间步上求解操作次序: 程序 A 开始计算 (1) 程序 B 等待数据 程序A结束计算并发送数据(2) 程序 A 等待数据 程序 B 获得数据并计算 (3) 程序B 发送数据 (4) 程序 A 计算 (5) 程序 A 发送 (6) 程序 B 继续 (7)Typical multi-physics simulations are:Fluid-Structure Interaction (FSI):First system: Fluid ow (Navier-Stokes equations)Second system: Solid mechanics (equilibrium)Quantities: Pressure (1 2), deformation(2 1)Thermomechanical couplingFirst system: Solid mechanics (equilibrium)Second system: Heat conduction (Fouriers law)Quantities: Temperature (2 1), deformation (1 2)Electrothermal couplingFirst system: Electrical conduction (Maxwells equations)Second system: Heat conduction (Fouriers law)Quantities: Temperature/electric conductivity (2 1), power loss/Joule heat (12)To find a solution for a coupled problem, all governing equations, which can be combined in a large system, must be solved. The solution in this way is called strong coupling. However, solving a system with strong coupling is often difficult as different approaches are necessary to solve the sub-problems.An alternative approach is through weak coupling. Here each problem is solved separately and some variables are exchanged and inserted into the equations of the other problem. This procedure usually yields a less exact solution compared to strong coupling. The advantages of the weak coupling are that the sub-problems can be solved faster than the complete system and that specialized solvers can be used for each.Figure 2: Staggered algorithm for solution of a coupled problem.The staggered method is sketched in Figure 2, which is one of the weak coupling approaches of MpCCI: Code A computes one step, sends data to code B, which then computes one step and sends data back to code A and so on. In addition to the staggered approach, MpCCI supports parallel execution of both codes. The selection of the coupling algorithm is described in . 2.8 Go Step Starting Server and Codes /.An important issue is the data exchange. The quantities must be transferred from one code to the other.This process can be divided into two parts:Association: Each point and/or element of the components of a coupling region is linked to a partner in the other system. The process of finding partners is also called neighborhood search, see . V-3.3 DataExchange /.Interpolation: The quantities must be transferred to the associated partner on the other mesh. In this process, the different mesh geometries, data distributions and the conservation of fluxes must be considered.MpCCI fully supports the data exchange between non-conforming meshes, i. e. the meshes of each subsystem can be deffined to optimize the solution of the subsystem.Figure 3: Co-simulation with MpCCI: Overview of the simulation processDefinition of the Coupling Process. Simulation codes and corresponding model files must be selected. The coupled regions, quantities and a coupling algorithm must be selected, further coupling options can be given. This step is completely supported by the MpCCI GUI.Running the Co-simulation. After starting the MpCCI server, both coupled codes are started. Each code computes its part of the problem while MpCCI controls the quantity exchange.先启动Mpcci，然后启动fluent及abaqusPost-Processing. After the co-simulation, the results can be analyzed with the post-processing tools of each simulation code, with the MpCCI Visualizer or with general-purpose post-processing tools.【结果后处理可在fluent、abaqus、Mpcci visualizer中进行】A simple exampleFigure 1. A simple coupled systemFigure 2: Exchange of quantities in the example FSI simulation2.2 model preparationBefore starting the coupled simulation, the models must be prepared in each code. In our example, this requires a model of the flow region and a model of the flap structure.Both models are created in the undeformed condition, i. e. the flap is straight. The computation of such a problem requires a CFD-code which can handle moving/deformable meshes.在fluent及abaqus中建立的模型都是没有发生变形。CFD软件必须能够处理moving/deformable meshes.It is recommended that you keep your FE and CFD model files in separate directories (see Figure 3). 推荐按figure 3所示，将FE、CFD、Mpcci的文件保存在不同的路径下because of the following reasons:_ Clear storage and maintenance of simulation data._ Ensuring that the codes do not overwrite files of other codes, when identical file names are used._ Simplification of the porting of the analysis when running the simulation on different platforms.Figure 3. Organization of the directories2.2.1 CFD ModelFigure 4: Fluid domain and CFD meshTo model the fluid domain, define the geometry in the CFD pre-processor and create a mesh.All boundary conditions must be defined as well如Figure 4.中蓝色的线所示. They comprise the flap surface, walls, inlet and outlet in Figure 4. Also for the coupling region boundary conditions may be set - this depends on the CFD code applied, please check the Codes Manual for details. Flap surface是coupling region，coupling region boundary conditions 的设定随CFD软件而变化。It is recommended to run the fluid problem on its own before starting a coupled simulation to be sure that the model setup is correct. In the present example the coupling region could be defined as a rigid wall for this purpose. If the model is not appropriate for computations with the CFD code alone, it is most likely that a co-simulation will either not run.在进行co-simulation之前必须进行单独的CFD计算，以保证CFD设置没有问题，能计算出结果。此时可将coupling region定义为rigid wall。如果CFD无法计算出结果，co-simulation肯定没有结果。2.2.2 FE ModelCompared to the CFD model which covers the fluid domain, the FE model covers the flap itself. Figure 5 shows a mesh of the flap with quadrilateral elements. The element sizes do not need to correspond to those of the fluid domain in any way as MpCCI can handle non-conforming meshes. FE model仅包括flap本身，flap的element不需与fluid domain相匹配，MpCCI能处理non-conforming meshing.The flap is connected to the top wall, i. e. the top nodes of the mesh must be fixed. flap 上端的单元node将被固定。注意固定的是nodeThe surface of the flap must be defined as a boundary to which the pressure load can be applied in the co-simulationflap 表面将被定义为在co-simulation时可加载pressure load的boundary. Although the system will not show any deformation without an external load, it is recommended to check the validity of the mesh and boundary conditions (i. e. the fixed nodes here) by running the FE problem alone and/or by performing a problem check if it is available in the FE code. To obtain a deformation you can replace the fluid forces by a similar load.在进行co-simulation之前FE也必须用一个与fluid force相似的load进行试算。Figure 5: Finite Element of the flap2.3 Starting the MpCCI GUIThe MpCCI GUI is started by executing the command mpcci gui from a shell console.The MpCCI GUI guides you through the steps to interconnect the FE and CFD models and to run the coupled simulation.2.4 Models Step Choosing Codes and Model FilesIn the Models Step, the following steps should be accomplished:_ Select the analysis codes to couple._ Specify their model files._ Set some code specific parameters if desired._ Scan the model files to determine the potential coupling regions.For the CFD-Code: Select the desired CFD-Code from the pull-down menu providing the available codes.After your selection the parameters and settings of the picked solver are shown underneath (see Figure 6).1. Select the CFD model file by clicking on the Browse button in order to choose the file via the file browser.2. You may also configure some additional parameters like the CFD version or release.3. Scan the model file by clicking on the Start Scanner button.Figure 6: Models Step for CFD-codeFor the FE-Code: Select the desired FE-Code from the list provided by the pull-down menu. After your selection the corresponding parameters and settings are shown underneath (see Figure 7).1. Select the FE model file via the file browser by clicking on the Browse button.2. Select the unit system.3. If the unit system is set to variable an additional parameter will be shown where you can select the grid length unit.Figure 7: Models Step for FE-code4. In addition you may change the settings for the FE release or the scan method.5. Scan the model file by clicking on the Start Scanner button.For each scanned model file the status is assigned to the corresponding analysis code:if the extraction of the interface regions was successful. if the scanner encountered problems during the scan which may depend on the parameters set for the analysis code.2.5 Coupling Step Definition of Coupling Regions and QuantitiesIn the Coupling Step the following steps need to be done:_ Define the coupling regions._ Select the components for each interconnected code._ Specify the quantities which will be exchanged.The components are automatically sorted by their element type. There are basically two types of components:Global Variables These components are data structures that are not related to the CFD or FEM grids. They contain global quantities like time or time step size. These components can be found under the Global element type label.Mesh Based Element ComponentsThese components comprise collections of mesh based elements and can be found under the Mesh label. They contain model parts and the related grid based quantities, e. g. nodal positions, heat values or forces. To build up the interconnection, elements should be gathered that are part of the coupling region. Therefore the components of the codes are collected in lists of zero-dimensional integration point elements, zero-dimensional point elements, one-dimensional line elements, two-dimensional face elements and three-dimensional volume elements (see Figure 8).【node set、element set、surface如何对应？】Figure 8: Integration Point, Point, Line, Face and Volume element labelsTo navigate between the two component types you have to click on the corresponding tab: Global or Mesh.Only active element types are offered (see Figure 9).In our example only the Mesh label is shown and already selected.Here in the code component list only Face elements exist, so only this one list is shown.For each component type the MpCCI GUI window is divided into three fields:MpCCI窗口从左到右分为3个区：Regions、Components、QuantitiesRegions with a list of the created coupling regions.Components with the lists of code components which may be selected into the coupled components lists, which define the coupling region.Quantities with a list of available quantities which may be selected and configured to be transferred from one application to the other on the selected coupling region.Figure 9: Coupling Step2.5.1 Define Coupling Regions 在Region中定义耦合区域Figure 10: Regions with context menuIn the field “Regions there is already the default region Mesh_1 defined. To change its name use Rename from the menu which pops up when you click with the right mouse button onto the region name. To add further coupling regions use the Add button at the top of the regions list (Figure 10).2.5.2 Select the Components for each Interconnected CodeIn the Components part for each code a list with available components for that particular code is shown.According to the valve example with the flexible flap this will imply: For CFD-code select the component flap-surface by double clicking, using drag & drop or using Add to Region Set from the pop-up menu (see Figure 11).For FE-code select the component outside in the same way as mentioned above.Figure 11: Coupled components selection2.5.3 Specify the Quantities which will be ExchangedIn the quantities list, select the quantities to be transferred by clicking on the checkbox near the name of the quantity (Figure 12). In MpCCI the names of the quantities are standardized. In our example we want to transfer pressure and deformation. In MpCCI the pressure is handled by the quantity RelWallForce在MpCCI中pressure用RelWallForce表示，如Figure 12所示Figure 12: Pressure configurationand the deformation by NPosition which stands for “nodal position. 在MpCCI中deformation用代表“nodel position”的NPoistion表示，如Figure 13所示Figure 13: Deformation configurationFor further information on the meaning of quantities see the Quantity Reference in the Appendix and . . For our example select and configure the following quantities: RelWallForce: for exchanging the pressure (see Figure 12). Sender is CFD-code. Its pressure unit is not editable because the unit system for the CFD-code is fixed to the “SI” unit system.pressure unit是不能更改 On the other hand you may select the appropriate unit for the FE-code because of the “variable” unit system setting in the Models Step (see Figure 7).NPosition: for exchanging the deformation (see Figure 13). Sender is FE-code. The unit for the deformation may be set as described above.For further information have a look at . V-4.4 Coupling Step.The definition of the coupling interface is completed, please click on the Next button to continue.2.6 Monitors Step Definition of Quantities for Monitoring定义所需monitor变量In the Monitors Step you can define some quantities for specific code components to be monitored. For the time being we wont apply monitors. Please click on the Next button to continue.2.7 Edit Step Further Coupling Options MpCCI提供了default value，对于大多数cases，default value is appropriateIn the Edit Step you may modify some MpCCI control parameters like_ online monitoring setting,_ parameters for search algorithm,_ switches controlling the output level for debugging or_ tracefile file format.An overview of all settings is given in . V-4.6 Edit Step .Figure 14: Edit StepThe MpCCI GUI provides default values for all settings which can be modified.The Edit Step window displays a tree of parameters on the left. On the right side the corresponding parameters are shown in a table as depicted in Figure 14. This table provides information such as_ the parameter name displayed with an orange background,_ the editable parameter value displayed with a yellow background,_ and a parameter description.To select a parameter click on the parameter name in the parameters tree. That followed edit the value by clicking the cell w